Final answer:
Glycolysis captures approximately 34 percent of the free energy available from a molecule of glucose, utilizing two phases involving an initial investment of ATP and subsequent energy capture netting two ATP and two NADH molecules.
Step-by-step explanation:
Glycolysis begins with a single molecule of glucose and ends with two molecules of a three-carbon sugar called pyruvate. The process of glycolysis captures approximately 34 percent of the free energy available in a molecule of glucose. This path of glucose catabolism is vital for cellular respiration and the extraction of energy for the cell's needs.
The process consists of two main parts, with initial investment of energy in the form of two ATP molecules to modify and split the glucose molecule. Subsequently, energy is extracted to form ATP and NADH. Despite the two ATP molecules invested, a net gain of two ATP and two NADH molecules is achieved.
Overall, considering that the glycolytic pathway can both feed into and interact with various other metabolic pathways and that some intermediates are used to synthesize other compounds, the efficiency of energy capture through glycolysis is significantly less than what could be theoretically possible, reflecting the complexity of biological systems.